scholarly journals Energy efficiency digital filter design for spectral analysis of primary electrical values

2019 ◽  
Vol 104 ◽  
pp. 02002
Author(s):  
Vladimir Mladenovic ◽  
Caslav Stefanovic ◽  
Sergey Makov
Keyword(s):  
Digital Filter ◽  
Filter Design ◽  
Point Of View ◽  
Electrical Networks ◽  
Analog Filter ◽  
Bilinear Transformation ◽  
Negative Sequence ◽  
Knowledge Based ◽  
Three Phase ◽  
Short Circuits

In this paper, the knowledge based design of digital filter for analysis of spectral components is illustrated. The primary electrical values are analyzed observing of the faults which appear by earth short circuits. The main point of view is negative sequence component and higher harmonics in distributed electrical networks. Method of symbolic processing is used to design digital filter that realizes negative sequence component. Designing of digital filter is based on active analog filter in the three-phase electrical networks using bilinear transformation. We use methods of computer algebra tools (Mathematica) to simulate processes in network. Also, we automatically derive properties of digital filter, and the knowledge embedded in symbolic expressions was used to simulate an example system. The characteristics of digital filter are given and annotated using different sampling frequency and entire cases of earth short circuits.

A Demonstration of Digital Filter Design, Implementation and Testing

1977 ◽  
Vol 14 (3) ◽  
pp. 221-236 ◽  
Author(s):  
T. J. Terrell
Keyword(s):  
Digital Filter ◽  
Filter Design ◽  
Second Order ◽  
Bilinear Transformation ◽  
Digital Filter Design ◽  
Effective Implementation ◽  
Recursive Digital Filter ◽  
Low Pass

The paper presents simple illustrative examples of recursive digital filter design using the bilinear transformation. The effective implementation of the design examples using a digital mini-computer is described. Practical tests and the corresponding results applied to a second order Butterworth low-pass digital filter are presented.

scholarly journals Researching the Blocking of Current Protection of Electrical Power Units with Transformers

2020 ◽  
Vol 63 (6) ◽  
pp. 491-499
Author(s):  
F. A. Romaniuk ◽  
V. Yu. Rumiantsev ◽  
Yu. V. Rumiantsev ◽  
A. A. Dziaruhina ◽  
P. I. Klimkovich
Keyword(s):  
Short Circuit ◽  
Electrical Power ◽  
Degree Of Saturation ◽  
Phase System ◽  
Asymmetric Mode ◽  
Negative Sequence ◽  
Three Phase ◽  
Short Circuits ◽  
Magnetizing Current ◽  
Higher Sensitivity

The magnetizing current inrush appears in electrical power units equipped with transformers in case of no-load energizing of the power transformers and in a number of other cases. This phenomenon could cause a false triggering of the current protection. To prevent incorrect actions of the current protection during the magnetizing current inrush a protection blocking is carrying out. The blocking principle operation is based on the fact that in a three-phase system in normal mode and in case of symmetrical short circuit the first harmonics contained in the phase currents of electrical installations form a direct sequence and the second ones – the negative sequences. In case of an asymmetric mode, including an asymmetric short circuit, the negative sequence appears, formed by the first harmonics that are part of the phase currents of the specified system. In magnetizing current inrush modes, second harmonics of significant magnitude are present in phase currents, which form the negative sequence. Based on the analysis of the information parameters of the specified sequences currents, identification of the magnetizing current inrush and short-circuit modes is performed with the implementation of the protection blocking if necessary. The study of the current protection blocking functioning was performed using computational experiment by analyzing the calculated changes of blocking parameter compared with the threshold setpoint. The specified researching is done by using the digital model that is implemented in the dynamic modeling environment MatLab-Simulink. As a result of the performed calculations, the principal operability of the proposed current protection blocking was confirmed that provides a fairly reliable identification of the magnetizing current inrush and short-circuits modes, regardless of the degree of saturation of current transformers. It was found that the proposed principle of the current protection blocking has a higher sensitivity in comparison with the classical one based on the estimation of the ratio of the second and first harmonics of the phase currents. In short-circuit modes in an electrical power units the proposed blocking causes a current protection operation delay that can be reduced by digital filters performance improvement. 

A MATLAB-based biomedical signal de-noising applied to digital signal processing course for third-year students

2018 ◽  
Vol 56 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Guo Luo
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Digital Filter ◽  
Digital Signal ◽  
Band Pass Filter ◽  
Analog Filter ◽  
Bilinear Transformation ◽  
Pass Filter ◽  
Educational Method ◽  
Low Pass Filter

Signal de-noising is one of the major topics of engineering application covered in an undergraduate-level digital signal processing course. Generally speaking, it involves a number of tedious concepts that have intrinsic physical meaning, which is difficult for students to understand . In this paper, an educational method using diaphragmatic electromyographic (EMGdi) as the de-noising object, which runs on the MATLAB software, has been developed for the convenience of learning and understanding for three-years students in digital signal processing course. This method transforms the analog filter to a digital filter by applying bilinear transformation equations, which allows the students explore the various characteristics of digital filter, such as low pass filter, high pass filter, band pass filter and band stop filter. That means Laplace equation transformed by inductance, capacitance and resistance will be replaced by the z equation, which is used for deriving sequence of difference equations. In the case studies, the clinical EMGdi is used to show the features of the developed method. Furthermore, classroom experience in the Nanfang College of Sun Yat-sen University has shown that the developed method helps in consolidating a better understanding of signal de-noising processing in digital signal processing course.

Digital Filter Application for Squelch on Industrial Frequency Noise and its Harmonic Waves Interference

2014 ◽  
Vol 668-669 ◽  
pp. 1059-1063
Author(s):  
Wei Jun Wen
Keyword(s):  
Digital Filter ◽  
Filter Design ◽  
Finite Impulse Response ◽  
Test System ◽  
Test Accuracy ◽  
Frequency Noise ◽  
Harmonic Waves ◽  
Analog Filter ◽  
Industrial Frequency ◽  
Multi Band

Industrial frequency and its harmonious waves are one of the main interferences in electronic measurement, which will cause severe influence on test accuracy. Digital filter is better than analog filter at resolution; furthermore multi-band stop digital filter design is unrealizable for analog filter design method. This paper designs an FIR(Finite Impulse Response) multi-band stop digital filter to reject the noise of 50 Hz and its harmonic waves from power network, whose stop bands are respectively as 48~52 Hz, 98~102 Hz and 148~152 Hz. Simulation results prove that the noise can be depressed to 30 dB. To analyze the filtered signal can improve accuracy of the test system. The whole course includes two parts, which are filter mathematical modeling and filter algorithm implementation on worksite data.

scholarly journals Optimization of digital filters performances simultaneously in frequency and time domains

2020 ◽  
Vol 8 (6) ◽  
pp. 63-77
Author(s):  
A. V. Smirnov
Keyword(s):  
Frequency Response ◽  
Digital Filter ◽  
Digital Filters ◽  
Simultaneous Optimization ◽  
Step Response ◽  
Analog Filters ◽  
Analog Filter ◽  
Bilinear Transformation ◽  
Time Domains ◽  
Filter Prototype

Wide used method of digital filters design consists in transformation of analog filter-prototype with required performances into digital filter. This method is applicable if the transformation preserves optimality of filter performances under specified set of quality indexes (QI). It was denoted earlier that such situation is possible when gain-frequency response (GFR) and phase-frequency response are optimized simultaneously. The task of simultaneous optimization of digital filters GFR and step response (SR) is also important but yet a little explored. Alternative method of this problem solving consists in search of digital filter transfer function (TF) which is optimal under GFR and SR QI’s. To investigate capabilities of the first method we found examples of analog filters Pareto-optimal under rise time and transient duration. Other QI’s of these filters fulfilled specified constraints. Then these filters were transformed into digital filters. Bilinear transformation and transformation with invariant impulse response were applied. Further we did the search of digital filters optimal under the same set of QI’s. In either method the hybrid heuristic algorithm was applied for search optimal solutions in the space of TF poles and zeroes coordinates. The results of investigation demonstrated that digital filters developed via search are superiorly under specified set of QI’s then digital filters developed via transformation of analog filters. Accordingly Pareto-optimality for QI of GFR and SR is not preserved during such transformation and direct search must be applied to optimized digital filters simultaneously in frequency and time domains. Further in some cases analog filters developed via reverse bilinear transformation of the found optimal digital filters are superiorly under the same set of QI’s then analog filters developed using search. In such cases using of digital filter-prototypes for design of analog filters is practical.

scholarly journals Impedance Matching-Based Power Flow Analysis for UPQC in Three-Phase Four-Wire Systems

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2702
Author(s):  
Xiaojun Zhao ◽  
Xiuhui Chai ◽  
Xiaoqiang Guo ◽  
Ahmad Waseem ◽  
Xiaohuan Wang ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Strategies ◽  
Impedance Matching ◽  
Flow Analysis ◽  
Point Of View ◽  
Impedance Model ◽  
Power Flow Analysis ◽  
Three Phase ◽  
System Node ◽  
Power Quality Conditioner

Different from the extant power flow analysis methods, this paper discusses the power flows for the unified power quality conditioner (UPQC) in three-phase four-wire systems from the point of view of impedance matching. To this end, combined with the designed control strategies, the establishing method of the UPQC impedance model is presented, and on this basis, the UPQC system can be equivalent to an adjustable impedance model. After that, a concept of impedance matching is introduced into this impedance model to study the operation principle for the UPQC system, i.e., how the system changes its operation states and power flow under the grid voltage variations through discussing the matching relationships among node impedances. In this way, the nodes of the series and parallel converter are matched into two sets of impedances in opposite directions, which mean that one converter operates in rectifier state to draw the energy and the other one operates in inverter state to transmit the energy. Consequently, no matter what grid voltages change, the system node impedances are dynamically matched to ensure that output equivalent impedances are always equal to load impedances, so as to realize impedance and power balances of the UPQC system. Finally, the correctness of the impedance matching-based power flow analysis is validated by the experimental results.

scholarly journals Turn-to-Turn Fault Diagnosis on Three-Phase Power Transformer Using Hybrid Detection Algorithm

2021 ◽  
Vol 11 (6) ◽  
pp. 2608
Author(s):  
Chien-Hsun Liu ◽  
Willybrordus H. P. Muda ◽  
Cheng-Chien Kuo
Keyword(s):  
Fuzzy System ◽  
Power Transformer ◽  
Detection Algorithm ◽  
Current Response ◽  
Negative Sequence ◽  
Three Phase ◽  
Hybrid Detection ◽  
Incipient Faults ◽  
Increase In Accuracy ◽  
Negative Sequence Current

A power transformer (PT) in power generation or transmission is critical to maintaining electrical continuity. Fault detection on a PT is needed, especially of incipient faults, which are often caused by a turn-to-turn fault (TTF) before it develops into a more severe fault. We use a hybrid algorithm between conventional and modern techniques to detect a developing fault in a PT. The current response signals from a negative sequence current directional algorithm, extended park vector algorithm (EPVA), differential negative sequence current, and EPVA-fuzzy system are combined to distinguish the possibility of a TTF. The subalgorithms are combined using a hybrid detection algorithm to distinguish the faults. The model is a 10 MVA, three-phase PT with Δ-Y configuration 150/300 kV, simulated using MATLAB Simulink software. The results show that by combining the subalgorithms, several limitations are distinguished within the TTF with a slight increase in accuracy.

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